


Mine, All Mine

by Electra_XT



Category: The Umbrella Academy (TV)
Genre: Anal Sex, Established Relationship, Fluff, M/M, Rimming, Sibling Incest
Language: English
Status: Completed
Published: 2020-01-12
Updated: 2020-01-12
Packaged: 2021-02-27 16:00:33
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,904
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22219693
Author URL: https://archiveofourown.org/users/Electra_XT/pseuds/Electra_XT
Summary: “No!” Klaus said. “Move the other way.”“What are you trying to get a good look at, exactly?” Diego said.Klaus blinked at him. His eyes were wide and kohl-rimmed, as fetching and alluring as the rest of him. “Why, your ass,” he said. “That thing isfine.”
Relationships: Diego Hargreeves/Klaus Hargreeves
Comments: 16
Kudos: 283





	Mine, All Mine

**Author's Note:**

> Written for this [umbrellakink prompt!](https://umbrellakink.dreamwidth.org/284.html?thread=1198108)
> 
> Title from “You Shook Me All Night Long” by AC/DC.

Diego had been working at the punching bag for twenty-five straight minutes, sweat trickling down his temple, when he caught sight of a long, lanky, feathered-coat-clad shape in his peripheral vision.

“Hey,” he said, straightening.

“Oh, hi,” Klaus said, leaning against the wall. He waved his HELLO hand at Diego, wiggling his fingers. “Don’t mind me.”

“Where’ve you been?” Diego said. “You were out of bed by the time I woke up.”

“Well, that’s because you woke up at ten,” Klaus said. 

“‘Cause I didn’t come home until three A.M.,” Diego said. He wiped his brow. “You don’t usually run errands on Monday mornings.”

“I went on a walk,” Klaus said. “Down through the city, down by the river. Good to get a little… exercise, you know?” He looked Diego over. “Not quite this _strenuous,_ though.”

“No pain, no gain,” Diego said. He hit the bag, making the chain from the ceiling rattle. “I’m almost done here. Then you can bug me.”

“Oh, take your time,” Klaus said, voice a purr.

Diego looked at him.

Klaus raised an eyebrow.

“What are you thinking about right now?” Diego said.

Klaus’s face lit up. “No one ever asks me that, Diego. God, no wonder we’re dating.”

“Didn’t really intend it to be a sweet nothing,” Diego said. Klaus’s face did look so gorgeous when he was excited, though. “It was more a sort of— you know when you see a cat with a dead bird in its mouth and you’re like uh-oh, spit that out right now?”

“Wow,” Klaus said. “Well, now I won’t tell you.”

“Klaus,” Diego said.

“No, no, it’s fine,” Klaus said. He waved a hand expansively. “Go back to your boxing. Your ever-important training. I won’t bother you with what’s on my mind, I’ll just stand here and cherish my good angle.”

“Your good what now?” Diego said.

“Go on,” Klaus said. “Punch it.”

“Is this your masochism thing?” Diego said, stepping away. “Because I’m not going to beat you up, I told you—”

“No, it’s not my masochism thing, get your mind out of the gutter, Diego,” Klaus said. “And now you’re ruining my angle. Go back.”

“The hell are you on about?” Diego said, and then he grinned. “Are you seriously just standing here and checking me out?”

“You sound so affronted,” Klaus said.

Diego bit his lip, smile uncontainable. It was good to have someone look at him for once. He’d spent so many years on his own, slipping through shadows and throwing knives from behind corners, practicing the art of being invisible. Klaus’s attention felt like a sun lamp, a laser beam, cranking up the light and love until Diego felt hot all over.

“I guess you can watch,” he said, stepping back to the bag.

“No!” Klaus said. “Move the other way.”

“What are you trying to get a good look at, exactly?” Diego said.

Klaus blinked at him. His eyes were wide and kohl-rimmed, as fetching and alluring as the rest of him. “Why, your ass,” he said. “That thing is _fine.”_

Diego felt a shiver through his entire body. He was used to being admired— he didn’t want to be vain, but he noticed how people’s eyes caught on his muscled chest, his nipple ring, his biceps, even in the turtlenecks he wore. But people never really called his ass out in particular, and it felt somehow more illicit than any other catcall or whistle he’d endured.

He turned away to hide his blush. “Well,” he said, half to the punching bag, “you can admire it for a little longer. I’ve got one more set to do.”

“You have an obsession,” Diego said.

It had been a long week. Diego’s car was slowly but surely going to shit, Al at the boxing gym was getting on his nerves, and the boiler room fluctuated wildly between sweltering and ice-cold. And all the time, whenever they were together, Klaus’s eyes were fixed on Diego’s ass.

Diego didn’t mind, exactly, but it always sent a strange shiver through him. He was starting to feel hot under the collar whenever he felt Klaus watching him— and at night, when they were tangled together, indelible images were beginning to trickle into Diego’s mind. Klaus’s palm finding Diego’s ass, fitting perfectly to the curve. Klaus backhanding it gently, giving it a light smack. Klaus’s thumb hooking under the band of Diego’s jeans and pulling down, laying him out on the bed, his clever fingers trailing down as Diego spread his legs, brushing against his—

He usually went absolutely still when he thought about it, holding his breath like he could keep his dick from twitching. Right now, he was finishing up the last of the dinner dishes, and he could physically feel Klaus’s eyes on him.

“I’ve had many obsessions over the course of my life,” Klaus said. “Makeup. Drugs. Those little fuzzy worm-on-a-string things.”

“Why?” Diego said.

“I mean, they’re really cool?” Klaus said. “I’d wear a feather boa made out of a bunch of them strung together, I think.”

“Not the worms, dumbass,” Diego said. “I meant why my…”

“Your perfect, God-given behind?” Klaus said.

Diego flushed.

“It’s really very simple,” Klaus said. He clapped his hands together. “Window shopping.”

“That makes no sense,” Diego said.

“No, no,” Klaus said. “It’s logical. If I can’t play with your incredibly sexy ass, I’ll look at it instead.”

Diego stopped still.

Klaus shrugged. “Anyway, I guess I could stop looking if you wanted, but I assure you it’s not malicious.”

“Why didn’t you ask?” Diego said. He was looking at a spot on the floor slightly to the left of Klaus.

“To play with your ass?” Klaus said. “Well, you told me you don’t… do that.”

“Did I?” Diego said.

“The first time,” Klaus said. There was a note of surprise in his voice. “Remember, Diego? You had me laid out on this bed, I asked you how you wanted it, and you said you’d only ever topped.”

“Yeah,” Diego said.

“And I didn’t contest, because I like getting fucked and I’m not a jerk,” Klaus said. He was looking at Diego askance. “But I’ve been having daydreams. Cravings. And I’m perfectly fine just looking, if it’s a hard and fast rule for you.”

“I never said it was a hard and fast rule,” Diego said.

He couldn’t look at him. Somehow, eye contact felt tantamount to vivisection. But Diego knew Klaus like he knew the back of his hand, and he trusted him— fuck, he loved him, they’d been living together for months— and he felt a spike of something between courage and shame as he lifted his gaze.

Klaus’s face was openly awed. “Oh,” he said softly. _“Oh.”_

“I still can’t get over the fact that you’ve never been fucked in the ass,” Klaus said, drizzling lube artfully over his fingers.

“Yeah,” Diego said tightly, rigid even though he was literally surrounded by pillows. “Somehow, I can.”

“I guess I can believe it,” Klaus said. “You always fell for that macho bullshit. Maybe you thought it was girly or something.” He smiled, wiggling his slippery hand. “Girls don’t have prostates, though.”

“Klaus,” Diego said, “don’t make this weird.”

It turned out that there was a pretty damn big gap between idly fantasizing about being fucked and spreading his legs for Klaus in practice. In all his imaginings, Klaus had simply… taken him, without all the fanfare. And it wasn’t like Diego was a stranger to anal— far from it, he thought, smirking at the ceiling— but somehow it felt excruciatingly more vulnerable when he was the one with his legs open on the bed.

“I’m not making it weird,” Klaus said, and he pushed one finger inside.

Diego went rigid. He didn’t mean to, but he couldn’t help it. “Shit,” he gritted out. “Sorry, I—”

“You’re like obscenely tight,” Klaus said. “Relax.”

“I am relaxing,” Diego said.

“Think about how incredibly horny you are to take my dick,” Klaus said.

“I _am_ incredibly horny,” Diego said.

“Really?” Klaus said, stifling a laugh. “Because you literally said that in the grouchiest voice I’ve ever heard.”

“Shut up,” Diego said, trying valiantly to enjoy the sensation of Klaus’s cold, wet finger inside him.

“Diego the Grouch,” Klaus mused. “Similar to Oscar, but less green. Still would live in a trash can, though.”

“I am going to break your fingers,” Diego said.

“Your clenching asshole is already breaking my fingers,” Klaus said. “Seriously, are you okay?”

“I’m fine,” Diego said.

Maybe there was something in his voice that betrayed how brittle Diego felt, because Klaus eased his finger out. “Hey,” he said, uncharacteristically gentle. “Don’t make me fuck you if you hate it.”

“I don’t hate it,” Diego said. He grimaced. His dick was going soft, and he felt like a failure. “It’s not your fault. I don’t know what’s fucking wrong with me, I— I want this.”

“I want it too,” Klaus said. He squeezed Diego’s hip. “And I really, really, really think you’ll like it, but I’m serious, it freaks me out to think about forcing you. So if there’s any way we can get you to relax…”

Diego sighed, lying back on the pillows. “It feels like a production.”

“But it doesn’t feel like a production when you’re fucking me,” Klaus said.

“Yeah, because I have my dick inside you and I can’t think,” Diego said.

“So we just need to get you to stop thinking.”

Diego closed his eyes. He’d been trying to meditate for years. Basic skill for fighters. He’d gotten used to the command of _empty your mind,_ the initial pressure and constriction of the silent moment, and he was getting better and better at wiping his thoughts clean—

He made a noise of surprise as Klaus’s lips met his, jolting back. Klaus laughed. “Hyper-vigilant weirdo,” he said, and he kissed Diego again.

“Oh,” Diego said, head dropping back. His mind was blank now. “Yeah, baby, that works.”

“Wow, kissing you was like your off button,” Klaus said. “Maybe we just need to make this an order of magnitude more chilled out than a rectal exam at the doctor’s.” He paused, and then his mouth curved up in an alarmingly Grinch-like smile.

“What,” Diego said, sitting up on his elbows.

“Oh, you’ll like it,” Klaus said. There was a gleam in his eye that meant Diego would either hate it or propose to him on the spot. He pushed Diego’s shoulders back down. “Don’t worry, _schatzi._ I’ve got this covered.”

_“Jesus Christ,” _Diego said, hands clenching into the sheets.__

__Between his legs, Klaus hummed, mouth deeply and obscenely occupied with tonguing Diego open. Diego’s whole body rippled with pleasure, hips arching involuntarily to meet Klaus’s mouth. “Fuck,” he said, voice audibly strained. “Klaus—”_ _

__It wasn’t like he hadn’t known about the concept of rimming, but it was way low on the list of things he usually employed, or asked for, during sex. He’d had guys who wanted it— he was a goddamn prodigy at oral sex, of course everyone wanted his mouth— but it always seemed too intimate, too messy, too much like a chore. Now, though— Diego held a fist to his mouth, biting down to keep from making some truly embarrassing noises._ _

__“You _like_ this,” Klaus said, surfacing. He sounded awed. His lips were slick. Diego’s cock twitched. “Fuck, Diego, who knew this was all it took?”_ _

__“Shut up,” Diego said, but it was breathy; completely unlike anything he’d gritted out earlier._ _

__“I won’t tell anyone,” Klaus said._ _

__“You better not,” Diego said. “‘Cause I can already think of something better to do with that mouth.”_ _

__“Good,” Klaus said, clearly delighted. Diego smiled down at him, a little dazed. “Hey, Diego?”_ _

__“What’s up, babe?” Diego said._ _

__“Can I…” Klaus wiggled his fingers. “Hear me out, hear me out. I know it screwed with your head the first time, but you’re relaxed now, right? And I might actually _die_ if no one ever touched your prostate, like I seriously think I’d die. For real.”_ _

__Diego looked at him. A dim red warning light flashed in the back of his mind, reminding him of a cold wet finger, an intrusion, his body going rigid. Klaus’s eyes were beseeching. Diego felt a pulse of adrenaline. Why was he so nervous about exposing himself to Klaus? He’d already welcomed him into his home, into his arms, into his fucking heart. Whatever neurotic whirlpool, he’d gotten stuck in it. He needed to get out._ _

__And after all, reckless shit had always been his forte._ _

__Klaus bit his lip. Diego hooked him in with his calves, towing him in with a thrill of lust. It felt delicious to push his own fucking limits._ _

__“Is that a yes?” Klaus said breathily._ _

__“Go for it,” Diego said. He grinned. “It’s all yours.”_ _

__

__Diego prided himself on his swagger, his ability to dirty-talk, but now that he was pushed on his back against the mattress, legs spread, filled like he’d never been before, every inch of composure went out the window._ _

“Klaus,” he said. His voice sounded foreign. _“Fuck.”_

__“There we go,” Klaus said. His hands tightened on Diego’s shoulders, those long fingers that had fingered Diego open so expertly. “Christ, Diego, I don’t think I’ve ever had anyone as good as you. You’re like if a male model walked out of a sleazy calendar and then took me out on a date and then let me move in with him—” His voice hitched, and even in his state of hazy incoherence Diego could tell he was trying to steer himself away from a ledge of emotion. “You’re like if a male model came to life and presented his miraculously perfect ass to me. Your ass, your thighs, I’m not sure you’re even real.”_ _

__“I’m real,” Diego said._ _

__“Wow, I am not fucking you hard enough if you’re still thinking about things like _facts,” _Klaus said.___ _

____“So fuck me harder,” Diego said. His voice was breathy, but somehow he couldn’t be bothered to feel ashamed. All of his attention was focused on the thick, heavy stretch of Klaus’s cock inside him, breaching him like nothing else ever had— he shuddered, a ripple of tension through his whole body._ _ _ _

____Klaus groaned. “Yeah, yeah,” he said, but he braced his hands on the mattress and began to thrust in and out in earnest. “Yeah, that’s— Diego, how are you so goddamn tight, _how?_ I mean I know how, but you’re perfect, you’re like—”_ _ _ _

____“I know,” Diego said. He reached a hand up and groped for Klaus’s face. “I know, baby.”_ _ _ _

____“Yeah,” Klaus breathed, as if he were stuck on the word. “Of course you do.” He screwed up his face in agony or pleasure or concentration. “God, Diego.” He pulled out and slammed back into Diego, hitting his prostate, making him whine. “That— is this what you want?”_ _ _ _

____“Own it,” Diego said. “You have me, Klaus, don’t be coy.”_ _ _ _

____Klaus’s eyes widened. Diego gazed up at him, completely fucked-out, totally in awe— maybe it was the myopia of the moment or the overwhelming sensation of being _taken,_ but he felt a surge of emotion, because what else had Klaus ever truly owned besides Diego?_ _ _ _

____“I don’t—” Klaus inhaled, then exhaled. He was keeping a steady pace with his thrusts, hips rolling, unrelenting, but his hands were shaking. “I— Diego—”_ _ _ _

____Diego moaned. Maybe he should have been soothing Klaus, giving him affirmative little noises, dropping platitudes to him like rewards, but neither of them had ever been exactly about that. He arched his hips up, trying to take Klaus deeper. “You don’t have to talk if you don’t want,” he said, voice strained. “I’m close, baby, I’m—” His hips twitched, and he let out a choked noise as Klaus’s dick rubbed perfectly against his prostate._ _ _ _

____“I love you,” Klaus said in a rush._ _ _ _

____It wasn’t the first time he’d said it. It wasn’t news. Diego knew that he and Klaus had always been entwined, never extricable from each other, but Klaus’s eyes were big and his slender, lean body looming over Diego’s— Diego cried out— Klaus’s hand came down to wrap around his dick, warm and firm and— Diego’s whole body bucked, consumed, and then he was coming, the feeling eclipsing him entirely as he spilled over Klaus’s hand._ _ _ _

____Klaus made a hitched sound. “Never get used to it,” he said. His voice was wobbly. “You— Diego, fuck—”_ _ _ _

____“Y’don’t have to apologize,” Diego slurred. He dropped his head back on the mattress. He felt boneless. “You wanna come, baby doll?”_ _ _ _

_____“Yes,”_ Klaus said. “Can— can I? Please?”_ _ _ _

____“You got it,” Diego said, and he spread his legs even further._ _ _ _

____It didn’t take long. Klaus’s thrusts became erratic, needy, and Diego grinned at the ceiling as Klaus came, letting out a high, breathy sound. Klaus swayed for a moment, and then he sank down onto Diego’s body._ _ _ _

____“Hey,” Diego murmured._ _ _ _

____“Hey, yourself,” Klaus said. He turned his head, kissing Diego’s chest. “So that was…”_ _ _ _

____“Love you,” Diego said, cutting him off._ _ _ _

____Klaus made a pleased, surprised sound. Diego reached up and tangled his fingers in his hair, scratching his scalp under the curls. “Thank you,” he said. It was almost a whisper._ _ _ _

____“Oh, Diego,” Klaus said. He scooted up so his face was pressed into Diego’s neck. “You don’t have to thank me for loving you.”_ _ _ _

**Author's Note:**

> [electra-xt](https://electra-xt.tumblr.com/) on Tumblr, taking prompts, come talk to me about TUA!


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